Peter Eisenman's Berlin/Holocaust memorial Light and Shadow. I like the way the structure of the building creates strong impressions of light and dark. Also the juxtaposition between the natural and man-made forces interests me.
This piece works with shadow art, which I find very interesting. I love pieces with crisp lines and the affect of the nails has exactly that. The contrast between the white wall, dark nails, and light shadows is dramatic, yet simple.